The present invention, in some embodiments thereof, relates to chemistry and, more particularly, but not exclusively, to energetic monomers, energetic macrocycles, energetic oligomers, energetic polymers and uses thereof.
Water-free fire protection systems are desired for providing superior protection for terrestrial, aerial and marine vessels, as well as for buildings, computer rooms, telecommunications facilities, museums and facilities operating emergency power generators, where exposure to water can cause a severe damage. These systems designed to rapidly fill the protected compartment with inert gas that can suffocate the fire, leaving practically no residues behind after they discharge. Similar requirements are present in the design and manufacturing of automotive airbags. The source of the inert gas can be storage tanks or chemical substances that can rapidly produce large quantities of inert gases. In some circumstances, the speed and capacity at which storage tanks can dispense inert gases are insufficient, and thus the most reliable and commonly used source of inert gases in such systems is the chemical substances.
Problems associated with chemical substances that can rapidly produce large quantities of inert gases are associated with the stability of these chemical substances, being highly energetic in some cases, and the toxicity thereof and of the residues they leave after discharge.
As a partial solution to the problem. CBrF3, known as Halon 1301, was used since 1960's in “clean” fire-protection systems, due to this material high efficiency in fire-extinguishing and relatively low toxicity. Unfortunately, it was found that Halon 1301 is associated with the significant damage to the ozone layer and its use and manufacturing was restricted or altogether stopped. Halon 1301 was replaced by more environmentally-friendly hydrofluorocarbons (HFCs); however, the latter materials were found to be 10-fold less effective in fire-extinguishing than Halon 1301 and HFCs' toxicity doses were found to be too close to concentrations of HFCs required for the fire-extinguishing. Moreover, upon exposure to an open flame, HFCs can decompose, releasing large quantities of a highly toxic and corrosive hydrogen fluoride that possesses great health hazards to occupants and rescue personnel, and damages equipment.
The materials capable to produce airbag's inflating gases should also be stable until detonated and be non-toxic. Nonetheless, the material which is still used today in many automotive airbags is nitrogen gas-generating compound sodium azide (NaN3). Although NaN3 has some advantages of operating at relatively low temperature, producing almost exclusively N2 as the output gas, the major problem associated with sodium azide is its extreme toxicity, being comparable to the toxicity of sodium cyanide, making the use-in-manufacturing and disposal of NaN3 very difficult and expensive, as well as a growing health hazard and grave environmental problem.
Energetic compounds have been used to inflate automobile airbags and aircraft occupant restraint bags. However, previously known nitrogen gas-generating materials are generally limited in one or more ways, e.g., they are overly impact-sensitive, difficult to synthesize on a large scale, difficult to shape, cast of mold, and generally not sufficiently energetic.
Castable energetic compounds are generally classified as either melt-castable or cast-cured. Melt-castable systems include those in which the energetic compound may be melted and cast into any type of mold. Cast-cured systems involve a mixture of one or more energetic compounds with a polymeric binder, cross-linker, plasticizer, and catalyst that is cast into any type of mold and allowed to cure in place.
While the bulk majority of energetic compounds and propellants are small, discrete molecules, the polymeric versions of these small molecules possess a number of significant potential advantages, which include, possibility to form intricate shapes by various processing methods (e.g. melt injection), potential for recovery/reuse (e.g. extrusion from a casing and then remolding), low inhalation hazard due to very low volatility even in a molten state, low dermal toxicity hazard (polymers are not readily absorbed through a skin by a direct contact), potential to control initiation and detonation velocity or rate of deflagration (propellants), by adjusting polymer chemical composition, microstructure and morphology. In general, energetic polymers are a class of energetic compounds, which are formed by polymerizing energetic monomers. In addition, energetic polymers may be formed by attaching energetic moieties to polymeric main chains (backbone functionalization). Energetic polymers can be both melt-castable and cast-cured, and can further be formed (polymerize) from their building blocks into any desirable shape.
A state-of-the-art overview of the various energetic polymers, employed for energetic compounds and propellant formulations, relevant to academic research and industrial R&D, as well as to industry and defense organizations, is provided in, for example, “Energetic Polymers”, by How Ghee Ang and Sreekumar Pisharath, ISBN: 978-3-527-33155-0; “Energetic Polymers and Plasticizers for Explosive Formulations—A Review of Recent Advances” by Arthur Provatas, 2000. DSTO-TR-0966; “Investigation of Nitrogen-Rich Polymers Based on Tetrazoles and Triazoles” by Stefan M. Sproll, 2009. Ph.D. Thesis under supervision of Prof. Thomas M. Klapötke; and “Nitrogen-Rich Energetic Materials Based on 1,2,4-Triazole Derivatives” by Alexander A. Dippold, 2013, Ph.D. Thesis under supervision of Prof. Thomas M. Klapötke.
U.S. Pat. No. 3,375,230 teaches polymers having a high nitrogen content and more particularly is concerned with organic nitrogen-containing polymers, having a nitrogen-to-carbon atomic ratio greater than 1.
Additional prior art is found, for example, in Kizhnyaev, V. N. et al., Polymer Science Series B. 2011, 53(5-6), pp. 317-323; Xue, H. et al., Journal of Polymer Science Part A: Polymer Chemistry, 2008, 46(7), pp. 2414-2421; and Klapötke, T. M. et al., Journal of Polymer Science Part A: Polymer Chemistry, 2010, 48(1), pp. 122-127.